The present invention is in the field of ophthalmic surgery and relates to an improvement in the device for mechanical enlargement or dilation of the pupil of the eye during surgery.
During phacoemulsification surgery and vitreo-retinal surgery, when the pupil does not dilate with medicated drops, a device is required for mechanical enlargement of the pupil. Such a device has to maintain the pupil in the enlarged state and prevent it from collapsing for the entire duration of the surgery. Removal of the device returns the pupil to an unenlarged state to preserve its function and cosmesis. Eyes with non-dilating pupils are often also associated with floppiness of the iris, which poses additional difficulty during surgery.
In phacoemulsification surgery for cataract, a 1.6 to 2.8 mm incision in the side of the cornea is required to insert a phaco probe. Smaller incisions result in secure and astigmatically neutral wounds translating into better visual outcomes.
Vitreo-retinal surgery requires 0.6 mm or smaller incisions in the sclera to insert instruments into the eye. Since a corneal incision is not required, such an incision, only to insert a pupil-dilating device, should be as small as possible.
Current devices in use for pupillary dilation require a 2.2 to 2.5 mm incision for insertion into the eye. They snag the incision because of gaps or pockets at the corners, which have a biplanar structure with a top and bottom part. Such snagging makes removal of the device difficult and causes damage to the cornea. They require precise alignment to engage the pupillary margin into the small narrow wedge shaped gaps or pockets at the corners. This is particularly difficult because the surgeon has a top view and the device itself obscures view of the narrow gap, which is at the side of the device. The gaps or pockets have two structural planes having an upper and lower part making the corners thick and bulky. The gaps or pockets hold the pupillary margin and iris tissue passively and the pupillary margin can easily disengage during surgical manipulations.
Such continuous ring devices have been disclosed in U.S. Pat. No. 8,323,296, Dec. 4, 2012 by Malyugin, US Patent Application publication 2012/0269786, Nov. 15, 2012 by Dusek and US Patent Application publication 2013/0096386, Apr. 18, 2013 by Christensen & Colvard.
Though discontinuous ring devices have been disclosed in U.S. Pat. No. 5,163,419, Nov. 17, 1992 by Goldman, U.S. Pat. No. 5,267,553, Dec. 7, 1993 by Graether, U.S. Pat. No. 6,620,098, Sep. 16, 2003 by Milverton and U.S. Pat. No. 6,648,819, Nov. 18, 2003 by Lee, these devices have not found acceptance because of larger incision size required, cumbersome manipulations involved and loose engagement.